Optimisation of the methodology for obtaining enzymatic protein hydrolysates from an industrial grape seed meal residue

Peptidomics profiling and biological activities of grape pomace protein hydrolysates

Grape pomace protein isolate was hydrolysed by Alcalase, Flavourzyme and Protease either individually or in combination to produce hydrolysates with antihypertensive and antimicrobial properties. The degree of hydrolysis (DH) ranged between 22 and 52 % for Protease and Flavourzyme, respectively. Among all treatments, hydrolysates prepared using Flavourzyme exhibited the highest angiotensin-converting enzyme inhibitory (ACEi) activity, with an IC50 value of 91 μg/mL. The peptidomics analysis revealed that the peptides identified in Flavourzyme hydrolysate presented molecular features compatible with its bioactivity, like a high density of ACEi sequences per peptide. The hydrolysates were also able to inhibit the growth of Escherichia coli in a range between 9 and 54 % for Alcalase and Alcalase + Flavourzyme, respectively. Peptides in the most active hydrolysate evidenced a high occurrence of proline residues, which is a structural feature of some antimicrobial peptides.

Identification and evaluation of antioxidant peptides from highland barley distiller's grains protein hydrolysate assisted by molecular docking

The aim of this study was to identify antioxidant peptides from highland barley distiller's grains and evaluate their antioxidant activity in vitro. The results showed that the enzymatic hydrolysate of highland barley distiller's grains prepared by ultrasonic assisted alkaline protease had antioxidant properties, aromatic amino acids accounted for 61.48% of the total free amino acids and acidic/basic amino acids accounted for 40.82% of the total hydrolyzed amino acids in enzymatic hydrolysate. Ultrafiltration component F1 (Mw < 1 kDa) had the highest DPPH, ABTS and hydroxyl radical scavenging activity and ferrous ion chelating activity, which were 93.92%, 69.59%, 50.27% and 0.71, respectively. Four peptides were identified and screened by LC-MS/MS and the P1 (SWDNFFR) and P4 (WDWVGGR) showed high scavenging ability of DPPH free radical (70.23%-62.84%) and ABTS free radical (30.87%-60.54%). Molecular docking showed that P1 and P4 formed multiple hydrogen bonds with central residues of MPO.

Microbial proteases and their applications

Proteases (proteinases or peptidases) are a class of hydrolases that cleave peptide chains in proteins. Endopeptidases are a type of protease that hydrolyze the internal peptide bonds of proteins, forming shorter peptides; exopeptidases hydrolyze the terminal peptide bonds from the C-terminal or N-terminal, forming free amino acids. Microbial proteases are a popular instrument in many industrial applications. In this review, the classification, detection, identification, and sources of microbial proteases are systematically introduced, as well as their applications in food, detergents, waste treatment, and biotechnology processes in the industry fields. In addition, recent studies on techniques used to express heterologous microbial proteases are summarized to describe the process of studying proteases. Finally, future developmental trends for microbial proteases are discussed.